Music and ambient sound improvements

[pierow]

If we want to make the music and ambient sound mp3s enabled by default there's still a couple more things to fix. The volume of the FMOD mp3s is now scaled by the game's volume cvar, so they're not too loud, but the looping ambient sounds still make a popping sound when the loop restarts. It's possibly a buffer underrun issue, so we can check the FMOD troubleshooting docs.

It would probably make sense to remove cl_musicdelay or turn it off by default so the music track only plays once at the start of the game. There's only as few tracks and having them continue to play random tracks at random intervals during multiplayer gameplay is in poor taste. We'll want to consider excluding the title theme track from being played during gameplay as well.

The .wav ambient sounds on certain maps could use a volume remix, like the marine start on co_angst. This should be easy enough by editing the entity values in a bsp editor.

Also, having the ambient sound and music volume options be more obvious in the audio options tab would be ideal so people can easily turn it off without having to hunt for the advanced options. Potentially this can be done if VGUI2 gets implemented.

[romulasry]

Valve Makes All Steam Audio SDK Source Code Available Under Apache 2.0 License
https://github.com/ValveSoftware/steam-audio/releases